The current noticeable climate change that has a significant impact on the environment and agricultural systems has become a serious concern for human society. Followed by the industrial activities of the global community and increased concentrations of greenhouse gases in the atmosphere, these changes are still considered as a threat to food safety and the environment. Changes in minimum and maximum temperature, rainfall amounts, and precipitation pattern, changes in CO₂ concentrations, and complex interactions between these factors and different crops are studied in the form of different probabilistic scenarios to get a glimpse of the future cultivation situation. Agriculture in Qazvin Plain is based on the water transferred from Taleqan Dam and groundwater. Since today these resources are facing issues like restriction on transfer and draw off, which is because of growth of interest in city dwelling, inappropriate water consumption patterns and over-exploitation, agriculture is sensitive to probable changes in water requirements and it is necessary to predict these changes for better management in the future. This study was carried out to investigate the effect of climate change on growth indices for three crops including wheat, barley, and maize in Qazvin Plain with different possible climate change scenarios, in the form of five large-scale climate models and three greenhouse gas emissions scenarios in 30 years’ time from 2021 to 2050 as well as from 2051 to 2080. Results showed that biomass production, grain yield, and water use efficiency in three crops of wheat, barley, and maize have increased up to 20–40% in future periods in Qazvin region climate. Growing degree-days (GDD) of these three crops have increased by 20%. Transpiration has risen by 10% in wheat and maize; however, it was stable on average in the first period and slightly decreased in the second period in barley. The transpiration coefficient has reduced by 5% for wheat and barley and has increased by 15% for maize. Results are valid as long as the initial growing conditions of these three plants are done as before, and the irrigation scheduling is performed according to the present period in spite of climate change.

当前对环境和农业系统产生重大影响的明显气候变化已成为人类社会的严重关切。随着全球社会的工业活动以及大气中温室气体浓度的增加，这些变化仍然被认为是对食品安全和环境的威胁。最低和最高温度，降雨量和降水模式的变化，CO _2的变化研究人员以不同概率情景的形式研究了这些元素的浓度以及这些因子与不同作物之间复杂的相互作用，以期了解未来的种植状况。加兹温平原的农业以塔勒坎大坝和地下水输送的水为基础。自今天以来，这些资源面临着诸如转移和流失的限制之类的问题，这是由于人们对城市住宅的兴趣增加，不适当的用水模式和过度开发所致，农业对可能的需水量变化敏感，因此有必要预测这些更改可在以后更好地进行管理。这项研究旨在调查气候变化对加兹温平原三种作物（包括小麦，大麦和玉米）生长指数的影响，以及不同的气候变化情景，在2021年至2050年以及2051年至2080年的30年中，以五个大规模气候模型和三个温室气体排放情景的形式呈现。结果表明，三种作物的生物量生产，谷物产量和水分利用效率在加兹温地区的气候中，小麦，大麦和玉米的未来增产幅度高达20-40％。这三种农作物的生长日数（GDD）增加了20％。小麦和玉米的蒸腾作用增加了10％。然而，大麦第一季平均稳定，第二季略有下降。小麦和大麦的蒸腾系数降低了5％，玉米的蒸腾系数提高了15％。只要这三棵植物的初始生长条件都像以前一样，结果才有效，